It’s one of the great questions of history, and indeed philosophy: what does it take to create a Hitler or a Stalin? What circumstances does it require to produce such evil? Newly released diaries from one of Joseph Stalin’s personal doctors suggest that, in Stalin’s case, illness could have helped to contribute to the paranoia and ruthlessness of his rule over the Soviet Union.

Alexander Myasnikov was one of the doctors called to Stalin’s deathbed when the dictator fell ill in 1953, and, in diaries that have been kept secret up to now, he claims that Stalin suffered from a brain illness that could have impaired his decision-making.

“The major atherosclerosis in the brain, which we found at the autopsy, should raise the question of how much this illness – which had clearly been developing over a number of years – affected Stalin’s health, his character and his actions,” Dr Myasnikov wrote in his diaries, excerpts of which were published for the first time in the Russian newspaper Moskovsky Komsomolets yesterday. “Stalin may have lost his sense of good and bad, healthy and dangerous, permissible and impermissible, friend and enemy. Character traits can become exaggerated, so that a suspicious person becomes paranoid,” the doctor wrote.